A prosthesis is an artificial device that is used to replace a missing body part (e.g., a limb). For example, a transhumeral prosthesis is an artificial limb that replaces an arm missing above the elbow. While prosthetic devices have been in use for centuries, early prosthetic devices were quite basic. With the advent of new materials, processors, and electronics, prosthetic devices have become more interactive. For example, a myoelectric prosthesis uses electromyographic (EMG) signals from voluntarily contracted muscles within a person's residual limb to control the movements of the prosthesis. The electromyographic signals may be used for elbow flexion/extension, wrist supination/pronation (rotation), hand opening/closing of the fingers, or other functions. Unfortunately, these traditional designs allow for only a single posture or for the user to cycle through a small number of pre-defined postures.